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MIC and Arsenic, extremes in bacterial life

Arsenic isn’t always a poison…

Some of the first letters learned in our earliest biology and chemistry classes are H, C, O, N, S and P, which are the single letter notations from the periodic table for elements Hydrogen, Carbon, Oxygen, Nitrogen, Sulfur and Phosphorus. These elements are essential and represent the most basic building blocks required for all organic life on the planet.

Extremophilic microorganisms are those that exist in conditions that unmodified would prevent organisms from growing. Examples of such extremes include temperatures above waters boiling point, acidic conditions more acid than the pH of hydrochloric acid, salt extremes like those in the Dead Sea, and many others with combinations of different extremes. Extremophilic bacteria adapt to such environments using any number of metabolic and structural mechanisms that convert a harsh external environment to a more accommodating microcosm. Although extreme, these organisms still utilize the same fundamental atoms for their molecular machinery and biochemical processes as all other microorganisms and mammals.

Our familiarity with Microbial Induced Corrosion (MIC) (or – Microbial Influenced Corrosion) is an example of microorganisms utilizing non-traditional environmental nutrients for their biological processes, such as sulfur, iron, or other components that result in the detriment of manmade structures such as steel pipes or concrete materials. But in all instances of microbial induced corrosion, the bacteria are functioning within normal parameters of utilizing the essential elements H, C, O, N, P, and S for their biological processes albeit in a manner somewhat differently from normally fast growing aerobic bacteria.

– Although it should be noted that most MIC associated bacteria are actually utilizing iron, sulfur or minerals in the way we utilize oxygen…

Phosphorus is a key element in many biological processes including the storage of biochemical energy (in ATP), the structure of DNA and RNA (or nucleic acids), and the machinery of the cell in the form of enzymes and the basic structure of our fats and lipids (phospholipids). In a recent publication in Science Magazine ( F. Wofle-Simon et. al., Science Dec. 2, 2010) researchers have isolated halophilic extremophiles (salt loving bacteria) that adapt to an essentially alien environment by replacing one of the known fundamental elements required for life, phosphorus for what is traditionally a poison, arsenic. For the first time, the researchers have demonstrated in their preliminary work, that a bacteria species was able to adapt to an environment lacking the essential element phosphorus and substitute arsenic in its place, allowing the organism to adapt, grow and replicate.

The implications of this exciting finding profoundly affect our day-to-day understanding about the flexibility of microorganisms and their adaptability to extreme environments.

Eliminating the use of phosphorus would be analogous to eliminating stop signs at intersections, all of the inter-reliant biochemical systems in the cell need to accommodate the loss. How the bacteria perform this task is the next big question that many researchers are likely now pursuing.

This is an early story for our understanding of what is happening inside these unique bacteria. Though not alien, as the details of the bacteria’s internal process become understood, it could truly reveal alien concepts for biological processes with implication for any number of industrial applications.

What is known from a long history in scientific study is that seemingly minuscule alterations to an organism can have tremendous affects on the network of interdependent cellular signaling, and biochemical processes. The potential impact from the broad substitution of an essential elemental would in kind be expected to have dramatic effects on the organism and could truly expand our concepts on the definition of biochemical life and the chemical processes that support such life.

Bacteria derived from harsh environments are expected to be the earliest forms of life, their adaptability and ingenuity create avenues for new and creative applications in our fundamental understanding of biological and scientific development.

The interest in this discovery is firstly that living bacteria accomplished this feat of seemingly defying key principles of biological sciences and secondly, in emphasizing that bacteria can be found virtually anywhere due to their capacity for adaptation and unwavering persistence.